The present invention is directed toward semiconductor structures, and more particularly to forming a dually strained silicon structure with different dielectric materials underneath the silicon.
Strain engineering is critical for improving complementary metal-oxide semiconductor (CMOS) performance. With continued downscaling of devices, the conventional external stress techniques (e.g., stress liners) run out of steam due to the diminishing spacing for incorporating those external stressors. Thus, as technology advances, channel strain becomes increasingly important.
Young's modulus, also known as the elastic modulus, defines the relationship between stress (force per unit area) and strain (proportional deformation) in a material. Specifically, Young's modulus is the ratio of the stress (force per unit area) along an axis to the strain (ratio of deformation over initial length) along that axis in the range of stress in which Hooke's law holds.